N Korea will never strike first against the West, certainly not against America, that's just silly talk. Not even China would allow their satellite to do that.
However, who knows what Putin is thinking, there are a few theories/scenarios that I pulled out of my behind.
First, I have little doubt that he despises the West helping Ukraine. The longer the war dragged on, the worse it was for him at home, his troops morale and geopolitical pressures that harm Russia. His annexing of these four territories today is partially driven by these concerns.
This required he secure a "win" of sorts, by confiscating this land, sending troops there to defend it, and, overseeing Ukraine water shipments. I don't know the demographical makeup of these areas, but the locations appear strategically placed for a potential future broader invasion at a time of his choosing, or, to try and run out the clock.
There is also the potential that Russian intel is on the ground using spies that have infiltrated Ukraine, siphoning Western money, selling some weapons on the black market, and making a few oligarchs even wealthier, while celebrating increased pressure by Western citizens on their government when they are unhappy with their own inflation and wealth decline. There is already less interest by citizens in the war since there are so many issues at home (which really confuses me why some governments would follow poor policies at a time when happy citizens are needed in the West).
World War III could be upon us soon but only if Europe still has the will. I believe if Russia and China are going to expand, they want to do so while a Democrat Establishment is in place. They might prefer the progressives types to lead, such as the Squad etc. as they are legitimately low performing push overs, but they certainly don't want to deal with a GOP government, even if lead by the Independent Trump.